We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital c...We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital controller, the proposed DPWM can not only offer temperature/process-independent pulse widths, but also operate at a much higher clock frequency than the existing delay-line/counter DPWM structure. Post-simulation results show that with our DPWM, the system clock frequency reaches 156.9MHz while the worst variation,in a temperature range of 0 to 100℃under all process corners,is only± 9.4%.展开更多
To promote the performance of the traditional multichannel filter bank which leads to speech quality degradation,an efficient design method of the non-uniform cosine modulated filter bank（CMFB） based on the audiogra...To promote the performance of the traditional multichannel filter bank which leads to speech quality degradation,an efficient design method of the non-uniform cosine modulated filter bank（CMFB） based on the audiogram for digital hearing aids is proposed. First, a low-pass prototype filter is designed by the linear iterative algorithm. Secondly,the uniform CMFB is achieved on the basis of the principle formulas. Then, the adjacent channels of a uniform filter bank which have low or gradual slopes are merged according to the trend of audiogram of the hearing impaired person. Finally,the corresponding non-uniform CMFB is obtained. Simulation results show that the signal processed by the proposed filter bank is similar to the original signal in a time-domain waveform and spectrogram without significant distortion or difference. The speech quality results show that the personal evaluation of speech quality（PESQ） of non-uniform CMFB is 35% higher than that of the traditional design, and the hearing-aid speech quality index（HASQI） increases by about 40%.展开更多
As for the application of electronic fuel injection （EFI） system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor ...As for the application of electronic fuel injection （EFI） system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor accuracy, a feed-forward control strategy based on load combined with proportional-integral-differential （PID） control strategy was proposed, and a digital speed controller applied to the electrical control system was designed. The detailed control strategy of the controller was intro- duced. The hardware design for the controller and the key circuits of motor driving, current sampling and angular signal captu- ring were given, and software architecture was discussed. Combined with a gasoline generator set mounted with EFI system, the controller parameters were tuned and optimized empirically by hardware in loop and bench test methods. Test results show that the speed deviation of generator set is low and the control system is stable in steady state; In transient state the control system responses quickly, has high stability under mutation loads especially when suddenly apply and remove 100% load, the speed deviation is within 8% of reference speed and the transient time is less than 5 s, satisfying the ISO standard.展开更多
This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and con...This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.展开更多
South Africa＇s tourism and travel industry is a key sector in its economy as well as a significant job creator. The recent global economic turmoil is threatening the tourism industry; at the same time, global experts...South Africa＇s tourism and travel industry is a key sector in its economy as well as a significant job creator. The recent global economic turmoil is threatening the tourism industry; at the same time, global experts claim that tourism may be a key to overcoming economic difficulties and play a vital role in the green new deal. The purpose of the study is to introduce a new strategic option that has become increasingly attractive for troubled businesses-barter. While the study focuses on the advantages of this concept＇s recent refinements for South Africa＇s tourism and travel industry, its findings are also applicable to other countries. A survey of small and medium-sized enterprises （SME） from Europe and Turkey, as well as graduate students at an Israeli university, demonstrate the gap between familiarity with barter processes and their advantages and the actual scale of barter transactions in the supply chain, in order to enhance the economic performance of their tourism enterprises as well as the entire economy, providing evidence for the potential of adapting old proven concepts to the modem digital world.展开更多
With the rapid development of digital technology in the new century, modem technology used to provide aid for teaching is widely used. The pattern of education had been great changed in due to input digital technology...With the rapid development of digital technology in the new century, modem technology used to provide aid for teaching is widely used. The pattern of education had been great changed in due to input digital technology .There are many tremendous changes such as the information collected and stored, the teaching process and performance, all aspects of the learner receives ways and means, especially the traditional art education be affected at the most significant way. In the traditional art teaching process, educators and learners mainly in the unarmed way of painting and design which tend to form on the art of teaching content recapitulate and mechanical reproduction of art materials for teaching situation. The art of teaching behaviors had become no creativity and creative fun. Modem art education needs innovation; needs to reflect the flavor of the era of technology. Therefore, the new model for art teaching with the perfect combination of the help of modem digital computer technology is becoming the most urgent needs.展开更多
The basics and applications of acousto-optic devices are described.The applications include acousto-optic spectrum analyzer,acousto-optic deflector,acousto-optic processors and acousto-optic digital matrix computer.
Research in virtualization technology has gained significant developments in recent years, which brings not only opportunities to the forensic community, but challenges as well. This paper discusses the potential role...Research in virtualization technology has gained significant developments in recent years, which brings not only opportunities to the forensic community, but challenges as well. This paper discusses the potential roles of virtualization in digital forensics, examines the recent progresses which use the virtualization techniques to support modem computer forensics. The influences on digital forensics caused by virtualization technology are identified. Tools and methods in common digital forensic practices are analyzed, and experiences of our practice and reflections in this field are shared.展开更多
Replacement and substitution encryption are two basic types of encryption historically. The classical encryption algorithm has been compromised now, but they still can play special role for modem cryptnlogy. For examp...Replacement and substitution encryption are two basic types of encryption historically. The classical encryption algorithm has been compromised now, but they still can play special role for modem cryptnlogy. For example, in digital image encryption system, substitution can disrupt the original order of the images and eliminate the correlation of image information which not only can realize security of images, but also can resist intentional attack and destruction of clipping and noise. And transposition transformation is introduced into the design of block ciphers. The substitution has the feature of high efficiency and resistance, which makes it meet the specific requirements of encryption. So substitution cypher can be applied to modern encryption system.展开更多
This paper presents a sliding mode observer for sensorless operation of SRM （switched reluctance motor） drive. Design of such an observer depends mainly on the nonlinear model of SRM. In this technique, neither extr...This paper presents a sliding mode observer for sensorless operation of SRM （switched reluctance motor） drive. Design of such an observer depends mainly on the nonlinear model of SRM. In this technique, neither extra hardware nor huge memory space are not required but it only requires active phase measurements. Furthermore, PI （proportional integral） and adaptive FLPI （fuzzy logic PI） controllers are suggested to operate individually along with the SMO （sliding mode observer） to cover a full speed range of sensorless controller. Both controller schemes operate in PWM （pulse width modulation） control mode. The proposed observer is implemented and tested using a digital signal processor. All results obtained with both simulation and experimental investigations corroborate the superior performance of the adaptive fuzzy logic controller （FLPI） when compared with those of PI controller.展开更多
文摘We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital controller, the proposed DPWM can not only offer temperature/process-independent pulse widths, but also operate at a much higher clock frequency than the existing delay-line/counter DPWM structure. Post-simulation results show that with our DPWM, the system clock frequency reaches 156.9MHz while the worst variation,in a temperature range of 0 to 100℃under all process corners,is only± 9.4%.
基金The National Natural Science Foundation of China(No.61375028,61673108)China Postdoctoral Science Foundation(No.2016M601696)+2 种基金Qing Lan Projectthe Program for Special Talent in Six Fields of Jiangsu Province(No.2016-DZXX-023)Jiangsu Planned Projects for Postdoctoral Research Funds(No.1601011B)
文摘To promote the performance of the traditional multichannel filter bank which leads to speech quality degradation,an efficient design method of the non-uniform cosine modulated filter bank（CMFB） based on the audiogram for digital hearing aids is proposed. First, a low-pass prototype filter is designed by the linear iterative algorithm. Secondly,the uniform CMFB is achieved on the basis of the principle formulas. Then, the adjacent channels of a uniform filter bank which have low or gradual slopes are merged according to the trend of audiogram of the hearing impaired person. Finally,the corresponding non-uniform CMFB is obtained. Simulation results show that the signal processed by the proposed filter bank is similar to the original signal in a time-domain waveform and spectrogram without significant distortion or difference. The speech quality results show that the personal evaluation of speech quality（PESQ） of non-uniform CMFB is 35% higher than that of the traditional design, and the hearing-aid speech quality index（HASQI） increases by about 40%.
文摘As for the application of electronic fuel injection （EFI） system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor accuracy, a feed-forward control strategy based on load combined with proportional-integral-differential （PID） control strategy was proposed, and a digital speed controller applied to the electrical control system was designed. The detailed control strategy of the controller was intro- duced. The hardware design for the controller and the key circuits of motor driving, current sampling and angular signal captu- ring were given, and software architecture was discussed. Combined with a gasoline generator set mounted with EFI system, the controller parameters were tuned and optimized empirically by hardware in loop and bench test methods. Test results show that the speed deviation of generator set is low and the control system is stable in steady state; In transient state the control system responses quickly, has high stability under mutation loads especially when suddenly apply and remove 100% load, the speed deviation is within 8% of reference speed and the transient time is less than 5 s, satisfying the ISO standard.
文摘This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.
文摘South Africa＇s tourism and travel industry is a key sector in its economy as well as a significant job creator. The recent global economic turmoil is threatening the tourism industry; at the same time, global experts claim that tourism may be a key to overcoming economic difficulties and play a vital role in the green new deal. The purpose of the study is to introduce a new strategic option that has become increasingly attractive for troubled businesses-barter. While the study focuses on the advantages of this concept＇s recent refinements for South Africa＇s tourism and travel industry, its findings are also applicable to other countries. A survey of small and medium-sized enterprises （SME） from Europe and Turkey, as well as graduate students at an Israeli university, demonstrate the gap between familiarity with barter processes and their advantages and the actual scale of barter transactions in the supply chain, in order to enhance the economic performance of their tourism enterprises as well as the entire economy, providing evidence for the potential of adapting old proven concepts to the modem digital world.
文摘With the rapid development of digital technology in the new century, modem technology used to provide aid for teaching is widely used. The pattern of education had been great changed in due to input digital technology .There are many tremendous changes such as the information collected and stored, the teaching process and performance, all aspects of the learner receives ways and means, especially the traditional art education be affected at the most significant way. In the traditional art teaching process, educators and learners mainly in the unarmed way of painting and design which tend to form on the art of teaching content recapitulate and mechanical reproduction of art materials for teaching situation. The art of teaching behaviors had become no creativity and creative fun. Modem art education needs innovation; needs to reflect the flavor of the era of technology. Therefore, the new model for art teaching with the perfect combination of the help of modem digital computer technology is becoming the most urgent needs.
文摘The basics and applications of acousto-optic devices are described.The applications include acousto-optic spectrum analyzer,acousto-optic deflector,acousto-optic processors and acousto-optic digital matrix computer.
文摘Research in virtualization technology has gained significant developments in recent years, which brings not only opportunities to the forensic community, but challenges as well. This paper discusses the potential roles of virtualization in digital forensics, examines the recent progresses which use the virtualization techniques to support modem computer forensics. The influences on digital forensics caused by virtualization technology are identified. Tools and methods in common digital forensic practices are analyzed, and experiences of our practice and reflections in this field are shared.
文摘Replacement and substitution encryption are two basic types of encryption historically. The classical encryption algorithm has been compromised now, but they still can play special role for modem cryptnlogy. For example, in digital image encryption system, substitution can disrupt the original order of the images and eliminate the correlation of image information which not only can realize security of images, but also can resist intentional attack and destruction of clipping and noise. And transposition transformation is introduced into the design of block ciphers. The substitution has the feature of high efficiency and resistance, which makes it meet the specific requirements of encryption. So substitution cypher can be applied to modern encryption system.
文摘This paper presents a sliding mode observer for sensorless operation of SRM （switched reluctance motor） drive. Design of such an observer depends mainly on the nonlinear model of SRM. In this technique, neither extra hardware nor huge memory space are not required but it only requires active phase measurements. Furthermore, PI （proportional integral） and adaptive FLPI （fuzzy logic PI） controllers are suggested to operate individually along with the SMO （sliding mode observer） to cover a full speed range of sensorless controller. Both controller schemes operate in PWM （pulse width modulation） control mode. The proposed observer is implemented and tested using a digital signal processor. All results obtained with both simulation and experimental investigations corroborate the superior performance of the adaptive fuzzy logic controller （FLPI） when compared with those of PI controller.
